fixed pid example in docs

Merge pull request #137 from milanofthe/block-sorting

handle eventful blocks separately from external events

Merge pull request #122 from milanofthe/roadmap-overhaul

the roadmap now automatically updates from the issue tracker

Merge pull request #107 from milanofthe/more-logging-info

add number of internal events to logging for adding blocks to simulation

Merge pull request #103 from milanofthe/block-lib-extension

cleanup and improvements to simulation loop and new blocks

Merge pull request #101 from milanofthe/improve-test-coverage

improve test coverage

Merge pull request #96 from milanofthe/simulation-interrupt

Simulation interrupt

Merge pull request #83 from milanofthe/fusion-block-lib

Library of Blocks that are specific for Nuclear Fusion and Fuel Cycle Modelling

Merge pull request #86 from milanofthe/solver-hierarchy-refactor

Solver hierarchy refactor

Update README.md, fixed grammar